A wind turbine pitch drive system comprises an electric grid for supplying electrical power, a motor for driving a pitch actuator, an electronic converter for controlling the motor and a back-up energy storage unit for supplying electrical power. The electronic converter comprises a DC-link capacitor bank. The system furthermore comprises a switching device for selectively connecting the DC-capacitor bank link to the back-up energy storage unit, and a frequency generator for controlling the switching device. Also disclosed is a method for protecting a component of the electronic converter.
Legal claims defining the scope of protection. Each claim is shown in both the original legal language and a plain English translation.
1. A wind turbine pitch drive system comprising: an electric grid configured to supply electrical power; a motor configured to drive a pitch actuator; an electronic converter configured to control the motor, the electronic converter including a DC-link capacitor bank; a back-up energy storage unit configured to supply electrical power; a switching device configured to selectively connect the DC-link capacitor bank to the back-up energy storage unit; and means for protecting the electronic converter from damaging in-rushing current by controlling the in-rushing current from the back-up energy storage unit to the DC-link, wherein the in-rushing current is the current that occurs when the back-up energy storage unit is substantially charged and the DC-link to which the back-up energy storage unit is connected is substantially discharged, and energy supply is switched to the back-up energy storage unit; and wherein the means for protecting comprises a frequency generator configured to generate a high frequency pulse based on a detected difference in voltage level between the back-up energy storage unit and the D-C link.
A wind turbine pitch drive system uses a backup energy storage (like a battery or ultracapacitor) to power the motor that adjusts the turbine blade angles (pitch). The system normally runs off the electric grid. When grid power fails, the backup storage kicks in. To prevent damage to the electronic converter controlling the motor when switching to backup power, especially due to a large in-rush current when the backup storage is charged and the DC-link capacitor bank is discharged, a frequency generator creates a high-frequency pulse. This pulse is based on the voltage difference between the backup storage and the DC-link. This pulse then controls a switching device to limit the in-rush current, protecting the converter.
2. The system according to claim 1 , wherein the back-up energy storage unit comprises at least one ultra-capacitor.
The wind turbine pitch drive system, including an electric grid, a motor to drive a pitch actuator, an electronic converter with a DC-link capacitor bank, a backup energy storage unit, a switching device and a frequency generator for in-rush current protection, utilizes at least one ultra-capacitor as the backup energy storage unit. This ultracapacitor supplies power to the motor during grid failures, and the system actively controls the current flow into the DC-link using a high-frequency pulse to prevent damage. The in-rush current is the current that occurs when the back-up energy storage unit is substantially charged and the DC-link to which the back-up energy storage unit is connected is substantially discharged, and energy supply is switched to the back-up energy storage unit.
3. The system according to claim 1 , wherein the back-up energy storage unit comprises at least one battery.
The wind turbine pitch drive system, including an electric grid, a motor to drive a pitch actuator, an electronic converter with a DC-link capacitor bank, a backup energy storage unit, a switching device and a frequency generator for in-rush current protection, utilizes at least one battery as the backup energy storage unit. This battery supplies power to the motor during grid failures, and the system actively controls the current flow into the DC-link using a high-frequency pulse to prevent damage. The in-rush current is the current that occurs when the back-up energy storage unit is substantially charged and the DC-link to which the back-up energy storage unit is connected is substantially discharged, and energy supply is switched to the back-up energy storage unit.
4. The system according to claim 1 , wherein the switching device is an insulated gate bipolar transistor.
The wind turbine pitch drive system, including an electric grid, a motor to drive a pitch actuator, an electronic converter with a DC-link capacitor bank, a backup energy storage unit, a switching device and a frequency generator for in-rush current protection, employs an insulated gate bipolar transistor (IGBT) as the switching device. This IGBT selectively connects the DC-link capacitor bank to the backup energy storage unit to supply power to the motor during grid failures, with current flow controlled by a high frequency pulse to prevent damage. The in-rush current is the current that occurs when the back-up energy storage unit is substantially charged and the DC-link to which the back-up energy storage unit is connected is substantially discharged, and energy supply is switched to the back-up energy storage unit.
5. The system according to claim 1 , wherein the switching device uses the high frequency pulse generated by the frequency generator to apply pulse width modulation to control the in-rushing current.
A system for managing in-rushing current in electrical circuits, particularly during startup or switching events, employs a high-frequency pulse generator and a switching device to regulate the current. The system addresses the problem of excessive in-rushing current, which can damage components or disrupt power distribution networks. The high-frequency pulse generator produces pulses that the switching device uses to apply pulse width modulation (PWM) to the in-rushing current. By modulating the pulse width, the system controls the current flow, preventing surges while ensuring stable power delivery. The switching device may include solid-state components such as transistors or thyristors, which respond rapidly to the high-frequency pulses to adjust the current dynamically. The system may also incorporate feedback mechanisms to monitor current levels and adjust the PWM parameters in real time, ensuring precise control. This approach is particularly useful in applications where sudden power demands, such as motor starts or capacitor charging, could otherwise cause voltage drops or equipment damage. The system enhances reliability and efficiency in power distribution and industrial automation by mitigating in-rushing current effects.
6. The system according to claim 1 , wherein the switching device uses the high frequency pulse generated by the frequency generator to apply pulse frequency modulation to control the in-rushing current.
The wind turbine pitch drive system, including an electric grid, a motor to drive a pitch actuator, an electronic converter with a DC-link capacitor bank, a backup energy storage unit, a switching device and a frequency generator for in-rush current protection, uses pulse frequency modulation (PFM) to control in-rush current. The switching device uses the high frequency pulse generated by the frequency generator to apply PFM to control the in-rushing current when the backup storage unit (e.g., battery or ultracapacitor) is connected to the DC-link capacitor bank. The in-rush current is the current that occurs when the back-up energy storage unit is substantially charged and the DC-link to which the back-up energy storage unit is connected is substantially discharged, and energy supply is switched to the back-up energy storage unit.
7. A method for protecting a component of an electronic converter in a wind turbine pitch drive system that includes: an electric grid configured to supply electrical power; a motor configured to drive a pitch actuator; an electronic converter configured to control the motor, the electronic converter including a DC-link capacitor bank; a back-up energy storage unit configured to supply electrical power; a switching device configured to selectively connect the DC-link capacitor bank to the back-up energy storage unit; and a frequency generator configured to control the switching device, the method comprising: detecting a difference between a voltage level of the DC-link capacitor bank of the electronic converter and a voltage level of the back-up energy storage unit such that the voltage level of the back-up energy storage unit is higher than the voltage level of the DC-link capacitor bank; generating a high frequency pulse, from the frequency generator, based on the detected difference in voltage level; and using the high frequency pulse to intermittently switch the switching device on and off to control an in-rushing current from the back-up energy storage unit.
A method for protecting an electronic converter in a wind turbine pitch drive system involves using a backup energy storage unit during grid failures. The system includes an electric grid, a motor to drive a pitch actuator, an electronic converter with a DC-link capacitor bank, a backup energy storage unit, a switching device, and a frequency generator. The method detects the voltage difference between the DC-link capacitor bank and the backup storage. If the backup storage has a higher voltage, the frequency generator creates a high-frequency pulse. This pulse rapidly switches the switching device on and off, controlling (limiting) the in-rush current from the backup storage to the DC-link, thereby protecting the converter components.
8. The method according to claim 7 , wherein the using of the high frequency pulse to intermittently switch the switching device comprises applying pulse modulation.
The method for protecting an electronic converter in a wind turbine pitch drive system, including detecting voltage differences, generating high-frequency pulses, and intermittently switching a switching device to control in-rush current, further refines the intermittent switching by applying pulse modulation. This means the high-frequency pulse isn't just used to turn the switch on and off, but the characteristics of the pulse itself are varied to control the current flow more precisely. The pulse modulation is applied to control an in-rushing current from the back-up energy storage unit.
9. The method according to claim 8 , wherein the pulse modulation applied is pulse width modulation.
The method for protecting an electronic converter, which includes detecting voltage differences, generating high-frequency pulses, intermittently switching a switching device using pulse modulation to control in-rush current, utilizes pulse width modulation (PWM) as the pulse modulation technique. This means the *width* of the high-frequency pulse is adjusted to precisely regulate the amount of current flowing from the backup energy storage to the DC-link capacitor bank, thereby limiting in-rush and preventing damage.
10. The method according to claim 8 , wherein the pulse modulation applied is pulse frequency modulation.
The method for protecting an electronic converter, which includes detecting voltage differences, generating high-frequency pulses, intermittently switching a switching device using pulse modulation to control in-rush current, utilizes pulse frequency modulation (PFM) as the pulse modulation technique. This means the *frequency* of the high-frequency pulse is adjusted to precisely regulate the amount of current flowing from the backup energy storage to the DC-link capacitor bank, thereby limiting in-rush and preventing damage.
11. The method according to claim 7 , wherein the detecting of a difference between the voltage level of the DC-link capacitor bank of the electronic converter and the voltage level of the back-up energy storage unit comprises measuring the voltage level of the back-up energy storage unit.
The method for protecting an electronic converter in a wind turbine pitch drive system, which includes generating a high-frequency pulse, and intermittently switching to control in-rush current based on voltage differences, specifies that detecting the voltage difference between the DC-link capacitor bank and the backup energy storage unit involves directly measuring the voltage level of the backup energy storage unit (e.g., battery or ultracapacitor). This measurement is then used to determine the necessary pulse characteristics for in-rush current control.
12. The method according to claim 7 , wherein the detecting of a difference between the voltage level of the DC-link capacitor bank of the electronic converter and the voltage level of the back-up energy storage unit comprises measuring a voltage level at the DC-link capacitor bank.
The method for protecting an electronic converter in a wind turbine pitch drive system, which includes generating a high-frequency pulse, and intermittently switching to control in-rush current based on voltage differences, specifies that detecting the voltage difference between the DC-link capacitor bank and the backup energy storage unit involves directly measuring the voltage level *at* the DC-link capacitor bank. This measurement is then used to determine the necessary pulse characteristics for in-rush current control.
13. The method according to claim 7 , wherein the detecting of a difference between the voltage level of the DC-link capacitor bank of the electronic converter and the voltage level of the back-up energy storage unit comprises measuring a voltage level at the electric grid.
The method for protecting an electronic converter in a wind turbine pitch drive system, which includes generating a high-frequency pulse, and intermittently switching to control in-rush current based on voltage differences, specifies that detecting the voltage difference between the DC-link capacitor bank and the backup energy storage unit involves measuring the voltage level at the electric grid. This measurement is used as an indication of grid failure, triggering the comparison to the backup storage voltage and initiating in-rush current control when the backup storage takes over.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
July 1, 2014
October 17, 2017
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